Field of the Invention
Embodiments of the invention generally relate to a swivel configured to rotationally decouple an upper section of a work string from a lower section of the work string while the work string is positioned in a wellbore.
Description of the Related Art
A wellbore is formed by rotating and lowering a work string, which has a drill bit connected at the lower end, into the earth. Fluid is circulated into the wellbore while the wellbore is being formed to remove the drilled earth and other wellbore debris. In particular, fluid is supplied down into the wellbore through an inner bore of the work string. The fluid will flow back up to the surface through the annulus formed between the outer surface of the work string and the inner surface of the wellbore, carrying out the drilled earth and other wellbore debris.
The wellbore is drilled until it reaches a reservoir within the earth. Sometimes, when the reservoir is reached, the fluid circulated into the wellbore flows into the reservoir, which hinders fluid circulation back to the surface and removal of the drilled earth and other wellbore debris. The drilled earth and other wellbore debris that are not removed will begin to accumulate at the bottom of the wellbore, as well as within the annulus formed between the outer surface of the work string and the inner surface of the wellbore. The accumulation of the drilled earth and other wellbore debris clogs the wellbore and prevents the lower end of the work string from rotating. Continued rotation of the work string from the upper end while the lower end is prevented from rotating causes the work string to twist, which can damage any connections or other tools that are part of and/or located between the lower end and the upper end of the work string.
When the reservoir is reached, the work string is prepared to be cemented in the wellbore. A packing element disposed on the work string at a location above the reservoir is actuated (such as by hydraulic pressure) into engagement with the wellbore to sealingly isolate the reservoir from the section of the annulus above the reservoir. A port disposed on the work string above the packing element is opened (such as by hydraulic pressure), and cement is circulated down through the inner bore of the work string, out into the wellbore through the port, and back up to the surface through the annulus formed between the outer surface of the work string and the inner surface of the wellbore. The packing element prevents the cement from flowing down into the reservoir.
It is desirable to rotate the work string while circulating the cement to help uniformly distribute the cement along the annulus. However, the work string is secured in the wellbore by the packing element. Rotation of the packing element while in sealed engagement with the wellbore can tear or otherwise damage the packing element. Additionally, even if the work string could rotate with or relative to the packing element, the lower end of the work string is still prevented from rotation due to the accumulation of the drilled earth and other wellbore debris as discussed above.
Therefore, there is a need for a new and/or improved methods and/or apparatus configured to selectively allow rotation of an upper section of a work string relative to a lower section of the work string.